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Commit 9ff01255 authored by Liu Bo's avatar Liu Bo Committed by Jens Axboe
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Blk-throttle: update to use rbtree with leftmost node cached 



As rbtree has native support of caching leftmost node,
i.e. rb_root_cached, no need to do the caching by ourselves.

Signed-off-by: default avatarLiu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 576ed913

block/blk-throttle.c

+15 −26
Original line number Diff line number Diff line
@@ -84,8 +84,7 @@ struct throtl_service_queue { 
	 * RB tree of active children throtl_grp's, which are sorted by

	 * their ->disptime.

	 */

	struct rb_root		pending_tree;	/* RB tree of active tgs */

	struct rb_node		*first_pending;	/* first node in the tree */

	struct rb_root_cached	pending_tree;	/* RB tree of active tgs */

	unsigned int		nr_pending;	/* # queued in the tree */

	unsigned long		first_pending_disptime;	/* disptime of the first tg */

	struct timer_list	pending_timer;	/* fires on first_pending_disptime */
@@ -475,7 +474,7 @@ static void throtl_service_queue_init(struct throtl_service_queue *sq) 
{

	INIT_LIST_HEAD(&sq->queued[0]);

	INIT_LIST_HEAD(&sq->queued[1]);

	sq->pending_tree = RB_ROOT;

	sq->pending_tree = RB_ROOT_CACHED;

	timer_setup(&sq->pending_timer, throtl_pending_timer_fn, 0);

}
@@ -616,31 +615,23 @@ static void throtl_pd_free(struct blkg_policy_data *pd) 
static struct throtl_grp *

throtl_rb_first(struct throtl_service_queue *parent_sq)

{

	struct rb_node *n;

	/* Service tree is empty */

	if (!parent_sq->nr_pending)

		return NULL;



	if (!parent_sq->first_pending)

		parent_sq->first_pending = rb_first(&parent_sq->pending_tree);



	if (parent_sq->first_pending)

		return rb_entry_tg(parent_sq->first_pending);



	n = rb_first_cached(&parent_sq->pending_tree);

	WARN_ON_ONCE(!n);

	if (!n)

		return NULL;

}



static void rb_erase_init(struct rb_node *n, struct rb_root *root)

{

	rb_erase(n, root);

	RB_CLEAR_NODE(n);

	return rb_entry_tg(n);

}



static void throtl_rb_erase(struct rb_node *n,

			    struct throtl_service_queue *parent_sq)

{

	if (parent_sq->first_pending == n)

		parent_sq->first_pending = NULL;

	rb_erase_init(n, &parent_sq->pending_tree);

	rb_erase_cached(n, &parent_sq->pending_tree);

	RB_CLEAR_NODE(n);

	--parent_sq->nr_pending;

}
@@ -658,11 +649,11 @@ static void update_min_dispatch_time(struct throtl_service_queue *parent_sq) 
static void tg_service_queue_add(struct throtl_grp *tg)

{

	struct throtl_service_queue *parent_sq = tg->service_queue.parent_sq;

	struct rb_node **node = &parent_sq->pending_tree.rb_node;

	struct rb_node **node = &parent_sq->pending_tree.rb_root.rb_node;

	struct rb_node *parent = NULL;

	struct throtl_grp *__tg;

	unsigned long key = tg->disptime;

	int left = 1;

	bool leftmost = true;



	while (*node != NULL) {

		parent = *node;
@@ -672,15 +663,13 @@ static void tg_service_queue_add(struct throtl_grp *tg) 
			node = &parent->rb_left;

		else {

			node = &parent->rb_right;

			left = 0;

			leftmost = false;

		}

	}



	if (left)

		parent_sq->first_pending = &tg->rb_node;



	rb_link_node(&tg->rb_node, parent, node);

	rb_insert_color(&tg->rb_node, &parent_sq->pending_tree);

	rb_insert_color_cached(&tg->rb_node, &parent_sq->pending_tree,

			       leftmost);

}



static void __throtl_enqueue_tg(struct throtl_grp *tg)